In busy chemical and pharmaceutical laboratories it is often desirable to quickly and accurately measure and deliver microvolumes of various reagents and samples for analysis. For this purpose, various vacuum pipettes have been developed in the prior art. These pipettes are quite commonly used in conjunction with disposable tips formed of injection molded plastic material such as polyethylene. Such a tip is disclosed, for example, in U.S. Pat. No. 3,732,734 issued May 15, 1973 to the present inventor. These tips are easily and quickly inserted on the ends of pipette tubes with which they form an air tight seal and are thereafter easily and quickly removable for disposal after use. Such disposability eliminates the need for sterilization between samples. The pipettes and tips known to the prior art serve only as measuring and delivering means and the fluids which are sampled and measured remain substantially unaffected.